Molecular Biology of the Cell - Gene Expression: From DNA to Protein

These flashcards cover key concepts about gene expression, including objectives, the central dogma, the structure of RNA, transcription, and translation processes.

What are the key objectives of this lecture on gene expression?

Distinguish between DNA and RNA structure and function, compare DNA/RNA polymerases, describe promoters and terminators, explain RNA processing in eukaryotes, define the genetic code, explain tRNA function, describe stages of translation, and the role of ubiquitination in protein degradation.

What is the central dogma of molecular biology?

The normal flow of genetic information in cells from DNA to RNA to protein, with RNA processing occurring in eukaryotes.

What is the primary difference in structure between RNA and DNA?

RNA has ribose instead of deoxyribose, uracil instead of thymine, is single-stranded, and is generally shorter and short-lived.

What is the role of RNA polymerase in transcription?

RNA polymerase transcribes DNA into RNA without needing helicase, single-strand binding proteins, primase, or ligase.

What is a promoter and how does it function?

A promoter is a specific DNA sequence recognized by RNA polymerase that orients it for transcription initiation.

Describe the modifications made to eukaryotic pre-mRNA.

Pre-mRNA undergoes capping and polyadenylation, with a 5' cap for processing and transport, and a poly-A tail to protect from degradation.

What is the genetic code?

The genetic code is triplet, nearly universal, and degenerate, meaning one amino acid can be specified by multiple codons.

What is tRNA's role in translation?

tRNAs transfer amino acids to ribosomes and match the correct amino acid to the corresponding codon on mRNA.

What happens during translation termination?

When a stop codon is encountered, a release factor binds to the A-site, leading to the hydrolysis of the polypeptide and disassembly of the translation complex.

What is ubiquitination and its role in protein degradation?

Ubiquitination marks proteins for degradation via the proteasome, which hydrolyzes ATP to feed in these marked proteins.